This is a reasonably good domain.  Whey protein is a good seller online, and it's nice to combine that with "nature's", i.e. a natural sounding term.  
I have to confess that for brands, I am now mainly concerned with getting the .com, so that is an issue, because it's a lot harder to sell the .co.uk as a brand in my opinion.  
That said, I still think this is quite a good name.  What are your plans for it?